The present invention relates to a first agent for oxidative hair dye containing an alkanolamine, and a method for stabilizing the color tone of an oxidative hair dye composition.
There has been known a hair dye composition exhibiting effects by mixing a plurality of chemicals. As such a hair dye composition, for example, there has been known an oxidative hair dye composition composed of a first agent containing an alkaline agent and an oxidative dye, and a second agent containing an oxidant such as hydrogen peroxide. The oxidative dye can be selected as necessary from known dyes from the viewpoint of a desired color, a desired brightness, a desired saturation, and the like. For example, in the field of fashion colors generally demanding high brightness and high saturation, oxidative hair dye compositions containing a predetermined amount of m-aminophenol, 5-amino-o-cresol, α-naphthol, or the like as an oxidative dye are used.
The alkaline agent improves hair-dyeing power by facilitating the action of the oxidant contained in the second agent and by swelling hair and improving permeability of a dye into hair. Ammonia and the like have been conventionally known as an alkaline agent used for an oxidative hair dye composition. However, there has been a problem that ammonia is accompanied by irritant odor when the amount of ammonia compounded is increased.
For example, an oxidative hair dye composition disclosed in Japanese Patent Laid-Open No. 2004-26834 has been known. Japanese Patent Laid-Open No. 2004-26834 uses alkanolamine as an alkaline agent to achieve the reduction of the odor derived from ammonia and to improve the hair-dyeing power.